Dissolved organic carbonwasmeasured bywet oxidation
with potassium persulfate in sealed ampoules following the
procedure, after a complete removal of inorganic carbon. Following the oxidation step, inorganic carbon derived from DOC was measured by gas chromatography as described above.
Samples for total inorganic carbon analysis (TCO2) measurements
were in situ transferred to gastight vials previously purged with UHP Helium, and analyzed for CO2 headspace content by gas chromatography after vial acidification with 100 μL 1 N phosphoric acid. Flux rates at each chamber were calculated from the differences in solute concentration between time-sequential samples and referred to the enclosed water volume, the surface area of the sediment enclosed, and the duration of the incubation period.